Scientists aim to be the first to reach the Earth’s mantle

The Japanese Agency for Marine-Earth Science and Technology (JAMSTEC) plans to drill down through the Earth’s crust and reach the mantle, the second of four layers which make up the Earth. While researchers have been attempting this elusive feat since the 1960s, if JAMSTEC and its partners succeed they will be the first to ever to do so.

The project will begin with a preliminary expedition undertaken by seafloor survey vessel Kairei, which, equipped with submarine vehicles and dredges, will use sonar to test the structure from the seafloor to a dozen kilometres underground. These tests will take place in September this year in waters northeast of Hawaii, with the coasts of Mexico and Costa Rica also to be considered for drilling.

Once a drill site has been chosen, the project will be handed over to JAMSTEC’s flagship vessel, Chikyu, equipped with drilling technology normally seen only on commercial oil drilling platforms. Chikyu will have to lower its drill through 4 kilometres of ocean before attempting to reach through the 6 kilometres of rock which make up the crust, the outermost layer of the earth. This may seem a long distance, but it is relatively thin—if the team were attempting the same feat on land, they would have to drill through dozens of kilometres of rock to reach their goal.

JAMSTEC hope to begin excavating as soon as the early 2020s, but there are financial concerns. The Integrated Ocean Drilling Platform (IODP) made plans to use Chikyu for a mantle expedition back in 2013, but the project was hit by severe budget troubles, and this new project has an estimated cost of ¥60 billion (roughly equivalent to £400 million).

The researchers hope that by sampling the mantle and the crust-mantle divide, it will be possible to better determine how the crust initially formed, giving us insights into the geological history of our planet.

Speaking to CNN, some of the JAMSTEC team expressed excitement about the prospect of finding microbial life deep under the Earth’s surface. In 2006, a group of Princeton-led researchers working in a South African mine some 2.8 kilometres below the surface discovered bacteria alive and well leading scientists to ask just how deep into the crust organisms can survive. The study of organisms who live in seemingly inhospitable conditions, so-called ‘extremophiles’, is exciting to many scientists as they give an insight to the adaptations developed in extreme conditions, possibly hinting at the characteristics of life on other planets.

The Japanese government also support the project with a more practical reason in mind: by developing better drill technology, drilling further than ever before, and discovering more about the mantle, many advancements can be made in predicting earthquakes—a major and common problem in Japan due to its location on the edge of the Eurasian continental plate. This will also help deal with devastating tsunamis and tidal waves which are often caused by undersea earthquakes.

The research vessel Chikyu has a history of earthquake prediction. It has been used in the past to investigate the join between the Philippine and Eurasian tectonic plates, which cause many of Japan’s earthquakes as they slowly scrape past each other. It may now be possible that the same vessel, drilling in pursuit of a geological holy grail that has been sought for over 50 years, can uncover crucial information about the first two layers of the Earth, with consequences not only for Japan, but across the world.